Face ID / Biometric Authentication

Use Face ID or Touch ID on iOS to authenticate approvals with a glance or a touch.

Key Concepts

Biometric authentication in SignedApproval uses the iOS Local Authentication framework to verify your identity with Face ID or Touch ID. This is the fastest way to approve requests on your iPhone — a single glance or touch confirms the approval.

Under the hood, biometric authentication uses the Secure Enclave on your iPhone to verify your face or fingerprint without sending biometric data to SignedApproval's servers. The biometric check happens entirely on-device; SignedApproval only receives a success/failure signal.

Biometric is available as an authentication method when using the iOS app only. On the web dashboard, use passkeys or TOTP instead.

Step-by-Step Guide

Install the iOS app

Download SignedApproval from TestFlight or the App Store. See iOS Getting Started for installation instructions.

Sign in

Sign in with your Google account — the same one you used to create your SignedApproval account. The app uses Supabase Auth with Google OAuth.

Enable biometric authentication

When you first attempt to approve a request in the iOS app, you'll be prompted to enable Face ID (or Touch ID on older devices). Grant the permission when asked. You can also enable it from the app's settings screen.

Approve with a glance

When a pending request appears, tap Approve. Your iPhone will prompt you with Face ID or Touch ID. After successful verification, the approval is signed and submitted.

How Biometric Differs from Passkeys

Both biometrics and passkeys can use Face ID or Touch ID as the user-facing verification step, but they work differently under the hood:

Passkeys (WebAuthn) — Use a cryptographic key pair where the private key is stored in the Secure Enclave. The browser handles the challenge-response protocol. Works on web and iOS.
Biometric (LocalAuthentication)— Uses iOS's native biometric API to verify the user, then tells the server the verification succeeded. Simpler, faster, but iOS-only.

In the signed approval payload, passkey approvals show method: "passkey" while biometric approvals show method: "biometric".

Note

If Face ID fails (e.g., you're wearing a mask or in low light), iOS will fall back to asking for your device passcode. This is standard iOS behavior and still counts as biometric authentication in SignedApproval.

Tip

For the fastest approval workflow: enable push notifications + biometric authentication. When a request comes in, tap the notification, glance at your phone, and the approval is done in under 3 seconds.

Passkey Setup iOS Getting Started Approving Requests